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Longacre Air Density Gauge

Brand: Longacre
Longacre Air Density Gauge



Your Price:$120.99
Retail Price:$124.90
You Save:$3.91(3%)
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Longacre Air Density Gauge
Get precise carb jetting every race. As air density changes with weather conditions, you should rejet your carb to keep horsepower and sharp response. Comes complete with case and jetting chart.Can only ship UPS Ground.


Standard engineering charts readily show the effect of air temperature and barometric pressure on engine power output. The maximum power output of an engine is directly related to "air density", provided the same fuel/air ratio is maintained. If the fuel/air ratio is permitted to go rich or lean, the reduction in power output is considerable greater. In addition, the ignition timing will be fast or slow and the spark plug heat range will be affected. To maintain a balance of these conditions and secure maximum power output at a given "air density" the correct fuel/air ratio must be maintained. The Air Density Gauge combines the factors of air temperature and barometric pressure and gives a direct reading in percent air density.

  1. Establish a starting point by tuning the engine jetting, spark advance, plug heat-range, etc., at a known "air density". This must be done through experimentation until the best performance is obtained.
  2. To maintain the proper fuel/air ratio as determined above, the carburetor/injector main jets must be changed to match new air density conditions. The area of the jets must be reduced or increased by the same percentage increase or decrease in "air density" as indicated by the Air Density Gauge. The chart shows the jet area for different size jet diameters.